fix diplomas select dropdown

assets/sass/_theme/sections/diplomas.sass

@@ -87,8 +87,8 @@ ul.diplomas
         position: absolute
         z-index: 2
         @include media-breakpoint-down(desktop)
-            right: half(var(--grid-gutter-negative))
-            left: half(var(--grid-gutter-negative))
+            right: var(--grid-gutter-negative)
+            left: var(--grid-gutter-negative)
         &,
         a
             color: black